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Touch Screen Controller

Rajas Yaso
Intellectual 280 points
Other Parts Discussed in Thread: AM3359

Hi

I am using Sitara AM3359 processor,Now i planned to interface a capacitive 3.5" inch touchscreen with the processor.In the processor datasheet,it has an inbuilt LCD CONTROLLER & Touch-Screen Controller.Then How do i know it is suitable for Resistive & capacitve TFTs because Resistive needs ADC pins and capacitive TFTs needs I2C pins from processor.

In  EVM-SK kit they use 4.3"  capacitive (Newhaven display) display,but how do i know,it is applicable for both resistive & capacitive TFTs from processor(datasheet) itself??

Thanks in advance

  • 0
    TI__Guru**** 393215 points
    Hi Rajas,
     
    The AM335X Touch-Screen Controller supports directly resistive touch-screens. Please check section 3.5 in the AM335X datasheet and Chapter 12 in the Technical Reference Manual.
  • 0 in reply to Biser Gatchev-XID
    TI__Guru**** 393215 points
    One more note. For the capacitive touch-screen used in the Starter Kit the Touch-Screen Controller is an external chip on the diplay assembly. It is controlled by the processor via I2C0, plus one interrupt and one wake-up line (SK schematics page 9, connector J2).
  • 0 in reply to Biser Gatchev-XID
    Intellectual 280 points

    Ya i note down it that Biser,In that Newhaven 4.3" inch LCD (NHD-4.3-480272MF-ATXI#-CTP) has two flexible PCB strips

       one for RGB data lines - ( 40 pin ,J1 connector)

       Second thing  - ( 6 pin ,J2 connector )

    In TMDSSK3358 harware user guide ,they noted as,This LCD doesn't required any controller. So I decided that ,Sitara am3359 had inbuilt TFT controller.

    Biser,Can you explain how does the above LCD works with or without controller???

    and also Clarify me about the Resistive & capacitive TFTs working on AM3359?????

     

  • 0 in reply to Rajas Yaso
    TI__Guru**** 393215 points
    Rajas,
     
    Touchscreen and LCD are two different things. They are physically assembled together in the display assembly, but they are controlled independently of each other. The AM335X does have an LCD controller, and also a resistive touchscreen controller. It does not have a capacitive touchscreen contoller, that's why for capacitive touchscreens an external controller is necessary. The Starter Kit probably has one on the LCD assembly (flex going to J2).
  • 0 in reply to Biser Gatchev-XID
    Intellectual 280 points

    Ya thanks biser,I found that. FT5306 is the Capacitive controller IC.But that ic is not in PCB it is assembled in TFT LCD  itself.

    If i planned to use Truly display,It doesn't had a controller so need to fix externally????

  • 0 in reply to Rajas Yaso
    TI__Guru**** 393215 points
    I don't know what display you intend to use, but make sure to uderstand that the touchscreen is not a part of the LCD itself. It's a separate component that is assembled together with the LCD itself, usually by the LCD manufacturer. If you want a display with touchscreen, a lot of LCD manufacturers offer them. And when you choose one check if the touchscreen is resistive or capacitive. If it's resistive it can be directly supported by the AM335X, if it's capacitive it will need an external controller, which may be on the LCD assembly itself (most probably), or you may need to place it on your board.
  • 0 in reply to Biser Gatchev-XID
    Intellectual 280 points

    Thank you,I understand your words.Thanks for your effort.

    I purchased 3.5" capacitve TFT without Controller.so i need to connect the Controller with the host processor or i meet an alternate vendor.

    Thank you biser.I'l stay in touch.Bye